Systems for providing either electrical stimulation of the brain or coupling fluid to or from the brain are coming into increased use for various purposes. Electrical stimulation of the brain is utilized for relief of chronic pain and treatment of movement disorders. A typical electrical brain stimulation system comprises a pulse generator operatively connected to the brain by a lead. The lead has one or more electrodes at its distal end, designed to be implanted within the patient's brain at a precise location, so that the electrode or electrodes are optimally and safely positioned for the desired stimulation. The lead is connected to the pulse generator at its proximal end, and also needs to be anchored with respect to a burr hole drilled in the patient's skull or cranium, in order to hold the distal end which carries the electrodes reliably secure. Likewise, in the case of a catheter for providing fluid to the brain or for providing drainage, it is necessary to be able to secure the distal portion of the catheter that passes through the skull and transfers the fluid at a predetermined exact location within the brain. Still further, for a combined catheter and lead member, such secure and reliable anchoring of the member so that the distal end is precisely located within the skull, is very important.
Reference is made to U.S. Pat. No. 5,464,446, "Brain Lead Anchoring System," assigned to Medtronic, Inc., which is incorporated herein by reference. The referenced patent illustrates an effective lead anchoring system, and it discusses the method of providing access through the skull by drilling a burr hole with a cranial drill, inserting a stimulation lead through the burr hole and positioning it so that the electrode or electrodes are at the desired stimulation site. The lead is positioned using a stereotactic instrument, which permits a very precise movement within the brain. Once the lead is positioned and tested to determine that the results of stimulation are satisfactory, it is critical that the lead is not to be moved, since even the slightest displacement can result in less than optimal results, and even injury to the brain.
The referenced anchoring system shows a basic anchor for fixing the lead in place with the distal portion extended through the cranial burr hole, and then securing it by bending it into a slit such that it is held by a friction fit. However, neither this system, nor any other known system, provides a reliable way for accurately securing the lead, or catheter, before it is bent into the fixation position. Thus, such systems do not provide against small movement of the distal end of the lead at the time of fixating, or securing the lead in place. What is required, and what has remained a substantial need in the art, is a system and method for accurately placing a cranial lead directly through the skull "in line," and without kinking, and which enables securing of the lead or catheter precisely in position relative to the brain before it is removed from the stereotactic instrument and connected either to a stimulator or fluid source. The cranial connector of this invention accomplishes this, and provides a sealed feedthrough for electrical or fluid connection from outside the skull to an area within the skull.